Production of high stability liquid vegetable oils

ABSTRACT

A process for obtaining a high stability liquid vegetable oil comprising partially hydrogenating a winterized vegetable oil having an iodine value of about 100 to 120 to an iodine value of about 70 to 90, cooling the oil and separating the solid components.

O Unlted States Patent 1 1 3,674,821 Gooding 1 July 4, 1972 [541 PRODUCTION OF HIGH STABILITY 2,814,633 11/1957 Gooding .l260/41E' LIQUID VEGETABLE OILS Primary Examiner-Joseph Rebold Inventor? Chester g, westfield, Assistant Examiner-Diana G. Rivers Attorney-Frank E. Robbins, John B. Goodman, Janet E. [73] Asslgnee' CPC International Price, Joseph Shekleton, Martha A. Michaels and Dorothy R. [22] Filed: Jan. 5, 1971 'Iihumler [2]] App]. No.: 104,140 57 A process for obtaining a high stability liquid vegetable oil [52] US. Cl. ..260/409, 260/428 comprising partially hydrogenating a winterized vegetableloil [BL w-Cllc 3/12, C1 15 having an iodine value of about 100 to I20 to an iodine value 0 Search of about to 90 cogling the oi] and separating the components. Ref CM [56] 6Claims,No Drawings UNITED STATES PATENTS 2,435,626 2/194 flooding 1 1. 26Q /428 PRODUCTION OF HIGH STABILITY LIQUID VEGETABLE OILS BACKGROUND OF THE INVENTION It is commonly known that refined vegetable oils can be useful for frying foods. Such oils, however, can be quite unstable at the high temperatures associated with frying, especially deep fat frying, and are not suitable for use for extended periods of time. High stability vegetable oils suitable for frying are now widely used in commercial cooking operations. These high stability oils are obtained by processes which involve hydrogenating refined vegetable oil to reduce the polyunsaturated fats in the oil. Especially suitable examples of such high stability oils are disclosed in US. Pat. No. 2,874,055 to Melnick and Gooding and US Pat. No. 2,814,633 to Gooding. These frying oils, however, are generally solid at room temperature.

High stability vegetable oils which are liquid at room temperature can be especially desirable. For example, such oils can be easily handled, i.e., they are easily transferred and measured, and liquid oils can impart desirable qualities to the products cooked with them.

Several methods are known for obtaining high stability vegetable oils which are liquid at room temperature. For example, U.S. Pat. No. 3,394,014 to Simmons, et al. discloses a process for partially hydrogenating a vegetable oil having at least 45% linoleic acid and cooling the partially hydrogenated oil from an elevated temperature to a temperature in the range of -25 C. to obtain crystal solids which can be separated from the liquid component. The resulting liquid component is a liquid shortening characterized by substantially no solids formation upon prolonged storage at 60 F (10.6 C). Such a process can be useful, The large amount of solids involved, however, can make the process cumbersome. For example, at high solids concentrations the mixture must be constantly agitated, or the crystals will interact to form a solid mass. In addition, it can be difficult to effectively separate the liquid component and solid component when the amount of solids involved is large.

SUMMARY OF THE INVENTION This invention presents a novel process for obtaining a high stability vegetable oil which is liquid at room temperature. In summary, the novel process of this invention comprises 1) partially hydrogenating a winterized vegetable oil having an iodine value of about 100 to 120 at a temperature of from about 200 to 290 F. to obtain a partially hydrogenated material having an iodine value of from about 70 to 90, (2) cooling the partially hydrogenated vegetable oil to a temperature of from about 55 to 85 F., (3) separating the resulting crystals to obtain a high stability liquid vegetable oil.

This process provides an excellent yield of high stability liquid vegetable oil. In addition, the process is advantageous in that excellent separation of crystal solids from the high stability liquid oil is readily accomplished.

DISCUSSION OF THE INVENTION AND ITS PREFERRED EMBODIMENTS This invention presents a novel process for obtaining high stability liquid vegetable oils which exhibit substantially no solids formation upon prolonged storage at 60 F. The process of this invention involves (1) partially hydrogenating a winterized vegetable oil having an iodine value of about 100 to 120 at a temperature of from about 200 to 290 F. to obtain a partially hydrogenated material having an iodine value of from about 70 to 90, (2) cooling the partially hydrogenated vegetable oil to a temperature of from about 55 to 85 F., (3) separating the resulting crystals to obtain a high stability liquid vegetable oil.

The winterized vegetable oils suitable for use in this invention have an iodine value of about 100 to 120, preferably about 100 to l 15, and a standard cold test value of about 1 hour or more. Such winterized vegetable oils are well known and can be obtained by a variety of procedures.

Winterizing a vegetable oil involves removing high melting components from vegetable oil, as for example, by cooling the vegetable oil and separating the high melting crystal solids formed from the oil. Methods for Winterizing vegetable oils are well known. (See, for example, Industrial Oil and Far Products, 2ed., by A. E. Bailey, pp. 868-72).

In general, the procedure for obtaining suitable winterized vegetable oils for use in this invention involves hydrogenating a refined vegetable oil, if required, to a suitable iodine value, and Winterizing the vegetable oil. Some vegetable oils, for example cottonseed oil, naturally occur with suitable iodine values and need not be hydrogenated prior to use in the process. Other vegetable oils, such as for example soybean oil, corn oil, safflower oil and sunflower oil must be panially hydrogenated to reduce the iodine value and then winterized. If the oil must be hydrogenated, preferably the hydrogenation is conducted at a temperature below 245F.

An especially preferred winterized vegetable oil for use herein is disclosed in US Pat. No. 2,627,467 to Gooding. This patent discloses a partially hydrogenated and winterized soybean oil having an iodine value of about 100 to I20. This preferred oil is obtained by hydrogenating soybean oil with a suitable catalyst, as for example a nickel catalyst or nickelcopper catalyst at temperatures below 245 F. After hydrogenation the oil is cooled and the solid crystal components in the oil are separated by filtration, centrifugation, decantation or other suitablemeans. Different crystallization conditions can be desirablyemployed depending upon the degree of hydrogenation to which the oil is subjected. For example, when an oil is hydrogenat'etl'toan iodine value of 100, the crystallization temperature may REE relatively high, such as to F. and preferably the oil is'fi obled relatively slowly, such as over a period of 2 to 3 days, whefeas when hydrogenation to an iodine value of 120 is desired, the crystallization temperature may be as low as 40 F or lower and the rate of cooling relatively rapid, such as 18 to 48 hours.

While the above-mentioned winterized vegetable oil is preferred for use in the process, other suitable winterized vegetable oils can be employed. The use of a winterized vegetable oil in the process is important since such an oil yields a relatively small quantity of crystal solids. These crystal solids can be surprisingly easily and effectively separated from the high stability oil.

In the process of this invention the winterized vegetable oil is partially hydrogenated at a temperature of from about 200 to 290 F., preferably from about 225 to 265 F., to an iodine value of about to 90, and preferably an iodine value of about to 85. While higher hydrogenation temperatures, as for example up to about 400 F. can be employed, the lower temperatures are preferred in that the lower temperatures contribute to better yields of the high stability oil.

Suitable catalysts which can be employed in the hydrogenation procedures mentioned herein before are the nickelcopper catalyst disclosed in US. Pat. No. 2,320,063 and the nickel catalyst disclosed in US Pat. No. 2,424,8l l. Hydrogenation pressures of about 40 to 50 p.s.i. are particularly satisfactory, although higher pressures, as for example 100 p.s.i. can be used. Suitable amounts of catalysts are from about 0.05 to 0.3 percent, preferably about 0.1 to 0.2 percent, by weight of the vegetable oil to be hydrogenated.

The partially hydrogenated vegetable oil obtained is cooled to a temperature of from about 55 to F., preferably to a temperature of about 65 to 75 F. Preferably the oil is cooled relatively slowly, such as for example, over a period of from about l2 hours to 72 hours. It is desirable for the oil to remain at the temperature to which it is cooled for a period of time, such as for example from about 6 to 24 hours.

After the partially hydrogenated oil is cooled the solid components in the oil are separated by filtration, centrifugation, decantation or other suitable means. The temperature to which the oil is cooled is maintained during the separation of the solid components.

The following examples are presented to specifically illustrate the invention disclosed herein.

EXAMPLE 1 Part 1 A suitable winterized vegetable oil is obtained in the following manner:

Twenty-one thousand pounds of soya bean oil of 136.2 iodine value was hydrogenated at 220225 F. and at 25 p.s.i. to an iodine value of 105.3 using a nickel catalyst sold under the name of Ruferts catalyst and described in US. Pat. No. 2,424,81 l. The hydrogenated oil was filtered to remove catalyst and was transferred to a tank fitted with cooling coils. The temperature was gradually lowered over a period of 40 hours to a low point of 61.5 F. At the end of 72 hours the crystallized portion was separated from the chilled oil by filtration under air pressure. There was obtained about 16,700 pounds of oil of iodine value of 106.0, which in the standard cold test gave a value of 1 hour.

Part 2 The winterized vegetable oil obtained in Part 1 was partially hydrogenated at a temperature of 245255 F. using 0.2%, by weight of the oil, of the above mentioned Rufert's catalyst. The hydrogenated oil was filtered to remove catalyst and was transferred to a tank fitted with cooling coils. The temperature was gradually lowered over a period of 12 hours to 76 F. The temperature was then lowered to 65 F. over a period of 24 hours. At the end of 36 hours the liquid-crystal mixture obtained was completely fluid and the crystallized portion was readily separated from the chilled oil by filtration under air pressure.

The liquid vegetable oil obtained was a high stability liquid vegetable oil which exhibits especially good stability at deep fat frying temperatures.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations. uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention.

What is claimed is: l. A process for obtaining a high stability liquid vegetable oil comprising 1. partially hydrogenating a winterized vegetable oil having an iodine value of about 100 to l20 at atemperature of from about 200 to 290 F. to obtain a partially hydrogenated material having an iodine value of from about to 90;

2. cooling the partially hydrogenated vegetable oil to a temperature of from about 55 to 85 F;

3. separating the resulting crystals to obtain a high stability liquid vegetable oil.

2. The process of claim 1 wherein the vegetable oil is soybean oil.

3. The process of claim 1 wherein the vegetable oil is cottonseed oil.

4. The process of claim 1 wherein the vegetable oil is corn oil.

5. The process of claim 1 wherein the vegetable oil is safflower oil.

6. The process of claim 1 wherein the winterized vegetable oil is hydrogenated to an iodine value of about to 85. 

2. The process of claim 1 wherein the vegetable oil is soybean oil.
 2. cooling the partially hydrogenated vegetable oil to a temperature of from about 55* to 85* F;
 3. separating the resulting crystals to obtain a high stability liquid vegetable oil.
 3. The process of claim 1 wherein the vegetable oil is cottonseed oil.
 4. The process of claim 1 wherein the vegetable oil is corn oil.
 5. The process of claim 1 wherein the vegetable oil is safflower oil.
 6. The process of claim 1 wherein the winterized vegetable oil is hydrogenated to an iodine value of about 75 to
 85. 